Method for producing a high-molecular weight flocculant

ABSTRACT

A high-molecular flocculant rendered water-soluble by conversion of cyano groups contained in a high-molecular material, a method for producing the flocculant, and a method for efficiently processing water using the flocculant. A high-molecular material containing acrylonitrile as a monomer is processed safely to impart hydrophilicity to the material and the resulting product is used for water processing to contribute to environmental conservation. An amino compound is added to a cyano group containing high-molecular material to convert at least a portion of the cyano group (—C≡N) into a molecular structure portion having an imidamino structure and, if necessary, to convert at, least the portion into one of an acid salt, a quaternary ammonium salt or a hydrolyzate structure portion to give a high-molecular flocculant. Alternatively, a high-molecular material having cyano groups is hydrolysed to convert the cyano group into carbamoyl groups, carboxylic groups or their salts to give a high-molecular flocculant. This high-molecular flocculant is charged alone or in combination the water for processing various.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. application Ser. No. 09/935,516, nowabandoned, filed on Aug. 23, 2001, which is a divisional of U.S.application Ser. No. 09/059,251, filed on Apr. 14, 1998 (now U.S. Pat.No. 6,316,507), which claims priority from the following JapaneseApplications: Application No. P09-0985849, filed Apr. 16, 1997;Application No. P09-104069, filed Apr. 22, 1997; and Application No.10-087374, filed Mar. 31, 1998. Applicant claims priority to and thebenefit of the above-identified applications, the disclosures of whichare expressly incorporated herein by reference to the extent permittedby law.

BACKGROUND OF THE INVENTION

This invention relates to a high-molecular flocculant renderedwater-soluble by conversion of cyano groups contained in ahigh-molecular material, a method for producing the flocculant, andmethod for efficiently processing water using the flocculant.

DESCRIPTION OF THE RELATED ART

In the field of processing waste water, a flocculant is used as areagent for causing aggregation and precipitation of micro-sizedparticles dispersed in waste water. In the waste water, such asindustrial waste water, it is a frequent occurrence that mud orhigh-molecular impurities are dispersed as colloidal particles. Theflocculant serves for aggregating these colloidal particles forpurifying the polluted water.

Of the wide variety of known flocculants, those having a molecularstructure of a long chain and exhibiting high hydrophilicity arehigh-molecular flocculants which are used extensively because additionof only a limited amount thereof to the colloidal particles leads tosignificant aggregating effects. The high-molecular flocculants areclassified into an anionic type, a cationic type and a nonionic typedepending on static charges on dissolution in water. Since a majority ofcolloidal particles are charged to the positive or negative polarity,extremely large flocs are formed to lower the turbidity highlyefficiently by properly selecting the high-molecular flocculantsdepending on the polarity of the static charges.

In the field of manufacturing industrial products, high-molecularmaterial, containing acrylonitrile as a monomeric unit, are usedextensively. Among the high-molecular materials containingacrylonitrile, there are polystyrene based resins, typified by nitriteresins, ABS (acrylonitrile-butadiene-styrene resins), SAN resins(styrene-acrylonitrile resin), AAS resins (acrylonitrile-acryl-styreneresins) and ACS resins (acrylonitrile-chlorinated polyethylene-styreneresin), acrylic fibers obtained on spinning a polymer havingacrylonitrile as a main monomeric unit, and NBR (acrylonitrile-butadienerubber, also termed nitrite rubber).

A resin molded product, containing acrylonitrile as monomeric units, issuperior in stiffness, dimensional stability and workability and henceis used frequently as a cover or a casing for various usages, a casingfor an electric appliance or a car or as a material for components.

The acrylic fibers are lightweight, bulky and is excellent in heatinsulating properties, skin touch feeling, weatherability andresiliency, so that they are used extensively for apparel alone or as amixture with other fibers, such as wool or cotton.

The nitrite rubber exhibits superior weatherability against oils, suchas fuel oil, machine oil or a tube oil, so that it is used as a fuelhose, oil seal or a belt and in particular for car use.

The acrylonitrile containing high-molecular material, used in a widevariety of industrial products, produces a large quantity of wastematerials in the course of fabrication of the industrial products or ondiscarding of the used-up industrial products. The waste high-molecularmaterials are generally disposed of by techniques such as incineration,earth filling or re-melting. The former two technique belongs todiscarding, while the later technique belongs to recycling.

The above-mentioned disposal techniques for the high-molecular materialsuffer from specified problems.

First, the incineration is accompanied by the problem of evolution oftoxic gases during combustion of the waste material. That is, highlytoxic cyan gas (HCN) is evolved due to cyano groups (—C═N) contained inthe acrylonitrile monomer unit and which constitutes one of side chainsof the polymer. Another factor contributing to incineration difficultiesis susceptibility to conversion into incombustible matter as a result ofcarbonization.

Re-melting is a technique of heat-melting the recovered waste materialfor re-molding, and represents an effective technique insofar asthermoplastic resins are concerned. However, the material tends to bedeteriorated in quality due to lowering in the molecular weight oroxidation, while being liable to mixing of foreign matter, such as dustand dirt. If waste materials of different originating points areprocessed collectively, technical and cost problems are raised, such asthe necessity of re-coloring due to coexistence of various coloringagents.

Thus, discarding by land filling is nowadays thought to be most propermeasures. However, selection and procurement of the proper site for aprocessing plant is becoming difficult from year to year, while theproblem of environmental pollution cannot be evaded withoutdifficulties.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a method formanufacturing a high-molecular flocculants having superior flocculatingproperties by a simple and safe manner using the high-molecular materialcontaining cyano groups as a starting material and a method foreffective disposal of waste water employing this high-molecularflocculant.

The high-molecular flocculant of the present invention, proposed foraccomplishing the above object, is such a flocculant in which at least aportion of cyano groups (—C—N) contained in the high-molecular materialis converted to impart water-solubility to enable the use of thematerial as a flocculant.

Specifically, in one aspect, the present invention provides ahigh-molecular flocculant having a molecular structure portion comprisedof an organic and/or inorganic amino compound added to at least aportion of cyano groups contained in a high-molecular material.

In another aspect, the present invention provides a high-molecularflocculant in which at least a portion of cyano groups contained in ahigh-molecular material has been converted into carbamoyl groups.

The former flocculant can be prepared by reacting the cyano groupcontaining high-molecular material with an amino compound, while thelatter can be prepared by hydrolyzing the cyano group containinghigh-molecular material.

In particular, if a used-up waste material from some other process isused as a high-molecular material for use as a starting material,resources can be exploited effectively by recycling thus contributing toenvironment conservation.

The high-molecular flocculant, thus obtained, can be injected into waterfor processing for water processing as a cationic or nonionic typehigh-molecular flocculant. It may also be used in conjunction with othernonionic, anionic or cationic high-molecular flocculant.

It is seen from above that the high-molecular flocculant according tothe present invention is obtained as a result ofhydrophilicity-imparting modification of the high-molecular materialcontaining cyano groups, in particular cyano groups originating fromacrylonitrile. Since the high-molecular material is likely to beproduced in large quantities as industrial wastes, the present inventionis highly effective in reducing toxic waste materials and effectiveutilization of resources.

Moreover, since this modification of the high-molecular material isachieved by addition of an amino compound or by a hydrolytic reaction,there is caused no problem such as emission of toxic gases duringincineration thus evading the problem of new environmental pollution inthe course of processing of waste materials. In addition, thehigh-molecular flocculant obtained as a result of processing of thewaste materials exhibits superior properties in connection with the rateof flocculation, turbidity of the supernatant liquid or in the watercontent of the cake. Therefore, use of the high-molecular flocculantobtained as a result of processing of the waste materials, for waterprocessing, leads to re-utilization of the usually discarded wastematerials, thus contributing not only to reduction of the toxic wastematerials and effective utilization of resources, but to environmentalconservation through purification of waste water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the mechanism for addition reaction, salt formingreaction and hydrolysis in connection with manufacture of ahigh-molecular flocculant of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

The high-molecular flocculant of the present invention is obtained byintroducing a highly hydrophilic molecular structure into at least aportion of cyano groups inherently contained in the high-molecularmaterial or by subsequently carrying out salt formation or hydrolysis incase of necessity for adjusting water-solubility or flocculatingproperties. If it is desired to impart sufficient hydrophilicity to theyielded high-molecular flocculant or to preclude yielding of hydrogencyanide with a view to safe waste discarding, it is preferred that themajority of cyano groups shall be converted into a highly hydrophilicmolecular structure portion.

The highly hydrophilic molecular structure portion may be exemplified bya molecular structure portion having added inorganic or organic aminocompounds or carbamoyl groups formed by hydrolysis of cyano groups.

As the amino compounds added to the cyano group in the former case,there are, for example, inorganic amino compounds, such as ammonia,hydrazine or hydroxylamine, and organic amino compounds, such as primaryor secondary amines in which one or two hydrogen atoms of ammonia aresubstituted by hydroxy groups. The carbon skeleton of the hydrocarbongroup may be saturated or non-saturated, of a chain or cyclic structure,straight-chained or branched. It is also possible for hetero elementsother than carbon, hydrogen or nitrogen, such as oxygen, sulfur orhalogens, to be contained in the skeleton of the hydrocarbon group.

Examples of the organic amino compounds include primary or secondaryamines, substituted by C1-C12 saturated or unsaturated chained or cyclichydrocarbon groups, primary or secondary amines containing two or moreamino groups in one molecule and the aforementioned primary andsecondary amines containing hetero atoms other than nitrogen in themolecule.

The primary and secondary amines containing two or more amino groups inone molecule may be enumerated by alkylene diamines, such as methylenediamine, ethylene diamine, trimethyl diamine (diamino propane),tetramethylene diamine (diamino butane), pentametylene diamine (diaminopentane), hexamethylene diamine (diamino hexane) or hexamethylenediamine (diaminoheptane), N-alkyl alkylene diamines, such as N-methylmethylene diamine, N-methyl ethylene diamine, N-benzyl ethylene diamine,N-methyl-1,3-diamino propane, N-butyl-1,3-diamino propane,N-dimethyl-1,3-diamino propane or N-butyl-1,3-diamino propane, alkylenepolyamines (not less than three substituents), such as diethylenetriamine, triethylene tetramine, tetraethylene pentamine, pentaethylenehexamine, polyethylene imine or piperidine and cyclic polyamines, suchas 1,2-diamino cyclohexane, xylylene diamine and diaminodiphenylmethane.

The amino compounds containing hetero atoms other than nitrogen in themolecule may be enumerated by hydroxyl alkylamines, such asethanolamine, propanolamine, butanolamine and pentanolamine. Ethanethiolamine may also be used.

Although there is no limitation to the amino compounds, polyaminecompounds, in particular ethylene diamine or 1,3-propane diamine, arepreferably used for reaction with the high-molecular material since thepolyamine compound can yield an imidazoline ring by reaction with cyanogroups.

The molecular structure portion, yielded by addition of an organic orinorganic amino compound, has an imidamino or imidazoline structure, andexhibits basicity due to the lone electron pair on the nitrogen atom.

If this nitrogen atom is linked by coordinate bond to a proton furnishedfrom the inorganic or organic acid, the nitrogen atom is chargedpositively to yield an acid salt. An inorganic acid, such as sulfuricacid, chlorosulfonic acid, chloric acid, nitric acid or phosphoric acidmay be used. As an organic acid, acetic acid, lactic acid, phthalic acidor phenols may be used.

If a halogenated hydrocarbon or sulfuric acid ester is given themolecular structure portion, the nitrogen atom of the molecularstructureportion is linked to the hydrocarbon group of sulfuric acid ester or thehalogenated hydrocarbon so as to be charged positively to yield aquaternary amine salt having the halogen as paired ions. The halogenatedhydrocarbon used at this time mat be enumerated by methyl chloride orbenzyl chloride, while the sulfuric acid ester may be enumerated bydimethyl sulfide or diethyl sulfide.

These acid salts and quaternary ammonium salts exhibit high watersolubility.

On the other hand, the latter (hydrophilic groups such as carbamoylgroup) is yielded by replacing at least a portion of the stronglyhydrophobic cyan group inherently contained in the high-molecularmaterial by a hydrophilic group, that is a carbamoyl group (CONH2) or bya carboxyl group (—COOH) or salts thereof (—COOX, where X is a cation).

This carbamoyl group or the carboxyl group is obtained by conversion ofa functional group by a hydrolytic reaction. This conversion of thefunctional group occurs in the sequence of a cyan group—a carbamoylgroup—a carboxyl group (or a salt thereof).

As a matter of course, it is necessary for the cyano group to becontained in the high-molecular material as a starting material for thehigh-molecular flocculant of the present invention in a form allowingaddition thereto of ammonia or an amino compound or in a form allowingfor substitution by a hydrophilic group. A high-molecular materialcontaining acrylonitrile (CH2═CH—CN) is preferred because the cyanogroup is linked as a side chain of the polymer molecule.

The molecular structure portions yielded on addition of ammonia,hydroxylamine, ethylene diamine, primary alkyl amine and ethanolamine tothe cyano group of the acrylonitrile monomer unit are collectively shownin FIG. 1, along with structures obtained on yielding of the imidazolinering by the action of ethylene diamine, acid salts, quaternary ammoniumsalts yielded on hydrolysis.

The above-mentioned high-molecular material may also be copolymers withother monomeric units (copolymers) without being limited toacrylonitrile homopolymers. These other monomeric units may beenumerated by one or more selected from the group consisting of acrylicacid, methacrylic acid, acrylic acid ester, methacrylic acid esters,butadiene, isoprene, chloroprene, vinyl chloride, acrylic amide,methacrylic amide, vinyl acetate, styrene, a-methyl styrene, ethylene,propylene, fumaric anhydride, malefic anhydride, itaconic anhydride,N-vinyl pyrrolidone and vinyl pyridine. The side chain of the ester bondof the acrylic acid ester and methacrylic acid ester is preferablyconstituted by saturated or unsaturated hydrocarbons having 1 to 10carbon atoms.

Among representative high-molecular materials, obtained on combiningacrylonitrile with the above-mentioned other polymers, there are, forexample, acrylic fibers, nitrite fibers, SAN resins(styrene-acrylonitrile resins), acrylonitrile-butadiene resins,acrylonitrile-butadiene-styrene resins, acrylonitrile-butadiene-acrylicresins, acrylonitrile-chlorinated polyethylene resin, nitrite rubber andacrylonitrile-butadiene rubber.

Meanwhile, if the above-mentioned high-molecular material is anacrylonitrile homopolymer, the content of the cyano groups is 100 mol %.However, if the high-molecular material is the acrylonitrile copolymer,the content of the cyano groups naturally is varied depending on thecontent of the acrylonitrile monomer unit. If the content of the cyanogroups is varied, the upper limit of the number of mots of the molecularstructure portion yielded by the addition reaction of the amino compoundand further the upper limit of the structure of hydrolysis yielded bychanges in the salt the molecular structure portion can yield or in themolecular structure portion are changed. Similarly, if the content ofthe cyano groups is changed, the upper limit of the number of mots ofthe carbamoyl group introduced later, the carboxylic group introduced inplace of the carbamoyl group on or the salts thereof are changed.

That is, if the content of the cyano groups is inherently small, thehigh-molecular flocculant of the present invention cannot exhibit highhydrophilicity or flocculating properties.

That is, according to the present invention, it is preferred that thecyano groups be contained in the high-molecular material in an amountcorresponding to not less than 15 mol % of the total monomer units, thatis that the content of the acrylonitrile monomer units be not less than15 mol %. This amount is preferably not less than 25 mol %.

Meanwhile, the high-molecular material has the weight average molecularweight (Mw) of approximately not less than 5000. If the molecular weightis lower than this limit value, the flocculating properties as thehigh-molecular flocculant tend to be lost.

The high-molecular material, as the starting material for thehigh-molecular flocculant according to the present invention, may, ofcourse, be a newly prepared material, that is a so-called virginmaterial. However, from the viewpoint of effective utilization ofnatural resources and prevention of environmental destruction, it isparticularly desirable to use a used-up waste material.

These waste materials may be exemplified by, for example, a casing, acover or a vessel used in electric appliances, cars, stationery,measurement instruments, building materials or in cosmetics. The wastematerials may be in the form of a mixture with other waste materials.Examples of these other waste materials include synthetic or naturalfibers, such as polyester, nylon, polyurethane, polyamides,polyphenylene ether, polycarbonates, polyphenylene sulfide, polyethyleneterephthalate, polybutylene terephthalate, silk, wool or cotton,occasionally containing a variety of additives, such as coloring agents,stabilizers, water retention agents, combustion retardants, plasticizersor fillers.

If the above-mentioned other waste materials are used in conjunction,the content of these other waste materials is preferably not more than60 wt %. If the content exceeds 60 wt %, the effect of the functionalgroups is strongly demonstrated such that desired water solubility isoccasionally not imparted to the yielded high-molecular flocculant.

Thus, although the waste materials may be those recovered fromfactories, retail stores or homes, the waste materials from factories orretail stores, where waste materials of the unitary composition arelikely to be produced in larger quantities, are more desirable thanthose recovered from holes and in which foreign waste materials tend tobe mixed more readily.

Turning to the method for producing the high-molecular flocculant of thepresent invention, if the high-molecular flocculant has a molecularstructure portion comprised of organic and/or inorganic amino compoundsadded to at least a portion of the cyano groups contained in thehigh-molecular material, it is sufficient if the above-mentionedacrylonitrile homopolymer or copolymer is used as a starting materialand is reacted with the organic and/or inorganic amino compounds.

This reaction can be carried out by directly injecting the startingmaterial into the amino compounds. After the end of the reaction, it ispossible to pour a solvent in which the high-molecular flocculant is notsoluble, such as acetone, into the reaction mixture in large quantitiesto re-precipitate the product.

Alternatively, the reaction can be carried out in an organic solvent,which may be a CS to C20 aliphatic chain hydrocarbon and/or cyclichydrocarbon, C1 to C4 halogenated hydrocarbons, dichlorobenzene,aromatic hydrocarbons, ethers, ketones, esters, or non-protonic polarsolvents, such as dimethyl sulfoxide (DMSO), dimethyl formamide (DMF),tetrahydrofuran (THF) or dioxane. If the organic solvent is used, thereaction product may be obtained as an aqueous solution by adding waterto the reaction system and distilling off the solvent after the end ofthe reaction.

During the reaction, sulfur-based catalysts, such as sulfur powders,thiourea or thioacetoamide, are preferably used.

Although there is no limitation to the concentration of the aminocompound during the reaction, it is preferably not lower thanapproximately 10%. If this concentration is too low, the speed of theaddition reaction tends to be lowered, or the reaction of addition tendsto be retarded. There is also no upper limit to the above concentration.If the reaction of addition is carried out by injecting a small amountof the high-molecular material into ethylene diamine, the concentrationof ethylene diamine is approximately 100%.

The reaction temperature for the reaction of addition differs with thetype of the high-molecular material used as the starting material, typeof the catalyst used, type of the solvent used for the reaction systemand with whether or not the solvent is used. If the reaction temperatureis 0 to 150° C., the reaction is allowed to proceed with practicallyacceptable speed and controllability. If the temperature is lower thanthis range, the reaction speed is lowered thus possibly lowering theproduction efficiency. Conversely, if the temperature is higher than theabove range; the high-molecular material tends to be lowered inmolecular weight to lower the efficiency as the flocculant. Thistemperature range is preferably 20 to 120° C. and most preferably 40 to80° C.

As for the reaction time duration, which depends on the type of theamino compound used, the reaction time of 30 minutes to 50 hours cangive a target product with a practically acceptable yield. If thereaction time duration is shorter than this range, sufficientmodification cannot be achieved. However, if once the chemicalequilibrium is reached, prolongation of the reaction time has nomeaning.

If, in the present invention, hydrolysis is to occur after the additionreaction of the amino compound, it can be carried out by acid hydrolysisemploying an acid catalyst or alkali hydrolysis employing a basiccatalyst.

As the acidic catalyst for acidic hydrolysis, inorganic acids, such assulfuric acid, sulfuric anhydride, fuming sulfuric acid, chlorosulfonicacid, hydrochloric acid, nitric acid or phosphoric acid, may be used.These inorganic acids may be used in conjunction with inorganicperoxides, such as aqueous hydrogen peroxide, in order to promote thehydrolytic reaction.

As the basic catalyst for the alkaline hydrolysis, hydroxides, hydrogencarbonates, carbonates or acetates of Li, Na, K or NH₄ may be used.

In any type of the alkaline hydrolysis, the high-molecular material maybe directly injected into inorganic acids, or into an aqueous alkalinesolution of an inorganic base. Alternatively, the hydrolysis may becarried out using the same solvent as that used for the above-mentionedreaction of addition. The catalyst concentration, reaction temperatureor the reaction time for hydrolysis may be set equivalently to therespective ranges discussed in connection with the above-mentionedreaction of addition.

The high-molecular flocculant, resulting from the above process, is ofthe nonionic type in the stage in which it has acquired the molecularstructure portion directly after addition of the amino compound, and isof the strong cation type on converting this molecular structure portioninto an acid salt or a quaternary ammonium salt. That is, with theabove-described manufacturing method of the high-molecular flocculant,it is possible to produce flocculants of the nonionic type and thecationic type by judiciously selecting and combining the stages of theprogress of the reaction of addition and the salt-forming reaction.

For converting the cyano group for introducing carbamoyl groups,carboxylic groups or salts thereof, the aforementioned acrylonitrilehomopolymers or copolymers are used as the starting material, that is asa basic material for hydrolysis.

The hydrolysis is roughly classified into an acidic hydrolysis employingan acidic catalyst and hydrolysis employing the basic catalyst. Any ofthese hydrolysis types may be used in the present invention.

As the acidic catalyst for the above-mentioned acidic hydrolysis,inorganic acids, such as sulfuric acid, sulfuric anhydride, fumingsulfuric acid, chlorosulfonic acid, hydrochloric acid, nitric acid orphosphoric acid, may be used. These inorganic acids may be used inconjunction with inorganic peroxides, such as aqueous hydrogen peroxide,in order to promote the hydrolytic reaction. Since the acidic hydrolysisof the high-molecular material containing cyano groups is satisfactoryin controllability, the reaction itself can be carried out in one stepby properly selecting the reaction temperature and the reaction time sothat a desired content of the carbamoyl groups will be achieved.

Although there is no particular limitation to the concentration of theinorganic acid, it is preferably set to approximately not less than 10%.If this concentration is too low, it may occur that the reaction speedof the hydrolysis is lowered or the hydrolytic reaction cannot proceedsufficiently. There is also no particular limitation to the upper limitof the concentration. If hydrolysis is carried out by charging a smallquantity of the high-molecular material into sulfuric acid, theconcentration of the inorganic acid is approximately 100%.

As the basic catalyst for the alkaline hydrolysis, inorganic bases, suchas hydroxides, hydrogen carbonates, carbonates or acetates of Li, Na, Kor NH₄ may be used.

However, alkaline hydrolysis is in need of a higher temperature than inthe case of the acidic hydrolysis described above, such that, if thistemperature condition is once achieved, the reaction proceeds speedily.The result is that the yielded high-molecular flocculant is lowered inmolecular weight, or the reaction of conversion of the cyan groupthrough a carbamoyl group to a carboxylic group or its salt proceeds ata time to render it difficult to control the introduced amount of ionicgroups, that is carboxylic anions.

Therefore, the basic catalyst is not used from the outset of thereaction, and is preferably used in the second stage in case of thetwo-stage hydrolysis. That is, acidic hydrolysis by the acidic catalystis first carried out in the first stage to prescribe substantially theamount of the carbamoyl groups introduced and alkaline hydrolysis isthen carried out in the second stage in order to convert a furtherportion of the carbamoyl groups into carboxylic groups or salt thereof.

In any type of the alkaline hydrolysis, the high-molecular material maybe directly injected into inorganic acids, or into an aqueous alkalinesolution of an inorganic base.

Alternatively, the above hydrolysis may be carried out in an organicsolvent, which may be a CS to C20 aliphatic chain hydrocarbon and/orcyclic hydrocarbon, C1 to C4 halogenated hydrocarbons, aromatichydrocarbons, ethers, ketones, esters, or non-protonic polar solvents,such as dimethyl sulfoxide, dimethyl formamide, tetrahydrofuran ordioxane.

The method for ultimate recovery of the high-molecular flocculant in theabove-described manufacturing method differs with the system of thehydrolytic reaction. If, for example, the high-molecular material isdirectly charged into inorganic acid, it is possible to pour a solventin which the high-molecular flocculant is not soluble, such as acetone,into the reaction mixture in large quantities to re-precipitate theproduct. If the solvent is used during hydrolysis, the reaction productmay be obtained as an aqueous solution by neutralizing an excess acidiccatalyst or a basic catalyst and by distilling off the solvent.

With the reaction temperature for hydrolysis ranging between 0 to 180°C., the reaction is allowed to proceed with practically satisfactoryspeed and controllability, although the reaction temperature differswith the types of the high-molecular material used as a startingmaterial, the catalyst constituting the reaction system, and thepresence or absence of the solvent. The reaction temperature is morepreferably 20 to 150° C. and most preferably 60 to 130° C.

The high-molecular flocculant, obtained as described above, is of thenonionic type by introducing the carbamoyl group and is of the anionictype by substituting carboxylic acid or carboxylates for a portion ofthe carbamoyl group.

Since the high-molecular flocculant of the present invention is at anyrate of the nonionic, cationic or anionic type, it may be used for waterprocessing in accordance with the usual method of exploiting thenonionic, cationic or anionic type high-molecular flocculant.Alternatively, the high-molecular flocculant of the present inventionmay be used in conjunction with various other flocculants.

The usable nonionic high-molecular flocculants may be exemplified by asynthetic system, such as polyacrylic amide, polymethacrylic amide orpolyoxyethylene, or natural systems, such as starch, guar gum, gelatineor the like sugar, or proteins.

The cationic high-molecular flocculants include quaternary products ofdialkyl aminoalkyl (meth)acrylate, where the quaternarification agentsinclude methyl chloride, dimethyl sulfate and benzyl chloride, or acidsalts thereof, where acid salts include inorganic acid salts, such ashydrochlorates or sulfates, and organic acid salts, such as acetates,polymers or copolymers thereof with (meth)acrylamide such as polymers ofmethyl chloride quaternary product of dimethyl aminoethyl acrylate or acopolymer thereof with acrylic amide. The cationic high-molecularflocculants also include quaternary product of dialkyl aminoalkyl(meth)acrylic amide or an acid salt thereof, and polymers or copolymersthereof with (meth)acrylic amide, such as copolymer of methyl chloridequaternary product of dimethyl amino propyl and acrylic amide. Thecationic high-molecular flocculants also include cationated modifiedproduct of polyacrylamide, such as Mannich modified product and Hoffmandecomposition product of polyacrylamide, and an epihadrin-aminecondensates, such as a polycondensate of epihadrin and C2 to C6 alkylenediamine. The cationic high-molecular flocculants also includepolydimethyl diallyl ammonium chloride, polyvinyl imidazoline and/orsalts thereof, dicyan diamide condensates, such as a formalin condensateof dicyanamide and ammonium chloride. The cationic high-molecularflocculants also include polyethylene imine, its quaternary product oracid salts thereof polyvinyl imidazole, its quaternary product or acidsalts thereof, poly-4-vinyl benzyl trimethyl ammonium chloride, chitosanand its salts. The cationic high-molecular flocculants also includeacidic hydrolyzates of N-vinyl formamide/acrylonitrile copolymer, itsquatemary product or acid salts, polyvinyl pyridine and tis quatermaryproduct or acid salts. The cationic high-molecular flocculants furtherinclude an alkylene dichloride and polyalkylene polyamine condensates,aniline-formaldehyde polycondensates, polyhexameythylene thioureaacetate, polyamino acids, such as polylysin, polyglutamic acid and itssalts.

The anionic high-molecular flocculants include partial hydrolyzates ofpolyacrylic amide and polymethacrylic amide, copolymers of acrylic acidor methacrylic acid and acrylic amide or methacrylic amide and saltsthereof. The anionic high-molecular flocculants also include acrylicacid or methacrylic acid and acrylic amide or methacrylic amide and2-acryl amide-methyl propane sulfonic acid or vinyl sulfonic acidternary copolymer and salts thereof. The anionic high-molecularflocculants also include sodium salts of alginic acid, Guar gum,carboxymethyl cellulose and starch, polystyrene sulfonic acid and saltsthereof. The anionic high-molecular flocculants further includesulfonated products and salts of polystyrene-based resin wastematerials, such as polystyrene, high-impact polystyrene, ABS resin, SANresin, nitrite rubber. The waste materials may contain up to 60 wt % ofpolyphenylene ether, polycarbonates, polyethylene terephthalates,polyamides and polyphenylene sulfide.

Of these high-molecular flocculants, sulfonated styrene-based polymersare desirable in that these exhibit high clarifying effect for a liquidsuspension and can be fabricated using waste materials as thehigh-molecular flocculant of the present invention.

Examples of the styrene-based polymers used for the high-molecularflocculants include styrene-butadiene, styrene-acrylonitrile,styrene-butadiene-acrylonitrile, styrene-(meth)acrylic acid,styrene-(meth)acrylate (aliphatic hydrocarbon having 1 to 4 carbonatoms), styrene-acrylonitrile-(meth)acrylate (aliphatic hydrocarbonhaving 1 to 4 carbon atoms), styrene-butadiene(meth)acrylate (aliphatichydrocarbon having 1 to 4 carbon atoms), styrene-malefic anhydride,styrene-acrylonitrile (meth)acrylate (aliphatic hydrocarbon having 1 to4 carbon atoms), styrene-butadiene-acrylonitrile and styrene-maleficanhydride. Preferred are styrene-butadiene, styrene-acrylonitrile,styrene-butadiene-acrylonitrile, styrene-malefic anhydride,styrene-acrylonitrile(meth)acrylic acid ester (aliphatic hydrocarbonhaving 1 to 4 carbon atoms) and styrene-butadiene (meth)acrylate(aliphatic hydrocarbon having 1 to 4 carbon atoms). Most preferred arestyrene-butadiene, styrene-acrylonitrile,styrene-butadiene-acrylonitrile, styrene-maleic anhydride.

The above-mentioned styrene-based polymers may be a newly preparedmaterial, that is a so-called virgin material, for producing thehigh-molecular flocculant, waste materials from factories, retail storesor homes (waste materials) or the combination of the virgin material andthe waste material. For re-exploitation of the polystyrene-based resinproducts, manufactured in large quantities as general-purpose resins,and for maintaining the earth's environments, it is more desirable touse the waste materials rather than the virgin materials, as thestyrene-based polymers.

If the waste materials are used, polymers other than the above-mentionedstyrene-based polymers may be contained in addition to the styrene-basedpolymers. These other polymers may be exemplified by polyphenyleneether, polycarbonates, polyphenylene sulfides and polyethyleneterephthalates. Most preferred are polyphenylene ether andpolycarbonates. The content of these other polymers is preferably notmore than approximately 60 wt %.

The above-mentioned styrene-based polymers are sulfonated in a solventcontaining sulfonating agents. The sulfonated styrene-based polymer isconverted into high-molecular flocculant by neutralizing the sulfonegroups and subsequently distilling off the solvent and the sulfonatingagent.

These sulfonating agents may be enumerated by sulfuric anhydride, fumingsulfuric acid, chlorosulfonic acid and concentrated sulfuric acid. Thesesulfonating agents may be used alone or in combination. As for theamount of addition of the sulfonating agents, these may preferably beused in an amount of 0.5 to 2 mols and more preferably in an amount of0.7 to 1.5 mol to 1 mole of the aromatic ring contained in thestyrene-based polymer (benzene ring in a side chain for a styrene-basedresin and a benzene ring in the main chain for a polycarbonate resin).If added in an excessively small amount, the sulfonation agent cannotsufficiently sulfonate the styrene-based polymer. Thus, in such case,the high-molecular flocculant cannot display its function as thehigh-molecular electrolyte. Conversely, if added in an larger quantity,gelated products are yielded during the sulfonating reaction orby-products, such as salts, are yielded in larger quantities. Therefore,in this case, a large quantity of impurities are contained in thehigh-molecular flocculant, thus lowering its purity.

For sulfonating the strene-based polymer, the above-mentionedsulfonating agent may be used in conjunction with the Louis acid, whichmay be enumerated by alkyl phosphate, such as triethyl phosphate ortrimethyl phosphate, dioxane, acrylic anhydride, ethyl acetate, ethylpalmitate diethyl ether and thioxane. The amount of addition of theLouis acid is 0.01 to 2.0 mol and preferably 0.02 to 1.0 mol of thearomatic ring contained in the styrene-based polymer (benzene ring in aside chain for a styrene-based resin and a benzene ring in the mainchain for a polycarbonate resin). If added in an excessively smallamount, gelated products tend to be yielded during the sulfonatingreaction. If conversely the Louis acid is added in an excessive amount,the sulfonating reaction itself is retarded to lower the yield of thehigh-molecular flocculant to raise production cost.

The solvent used for sulfonating the styrene-based polymers may beenumerated by C1 to C2 aliphatic halogenated hydrocarbons (preferably1,2-dichloroethane, chloroform, dichloromethane and 1,1-dichloroethane),and aliphatic cyclic hydrocarbons, preferably cyclohexane, methylcyclohexane and cyclopentane. These solvents may be used alone or as amixture. In mixing the solvents, there is no particular limitation tothe mixing ratio.

The above-mentioned solvents may be used as a mixture with othersolvents. These other solvents may be enumerated by paraffinichydrocarbons (with 1 to 7 carbon atoms), acetonitrile, carbon disulfide,tetrahydrofuran, tetrahydropyrane, 1,2-dimethoxy ethane, acetone,methylethylketone and thiophene. Preferred of the other solvents are C1to C7 paraffinic hydrocarbons, tetrahydrofuran, acetone andacetonitrile. Although there is no particular limitation to the mixingratio with the other solvents, the mixing ratio is preferably in a rangeo 1 to 100 vol %. The above-mentioned solvents may be recovered, such asby extraction or distillation, after the end of the sulfonating reactionof the styrene-based polymer, for re-use in the next sulfonatingreaction.

The above-mentioned anionic high-molecular flocculant can be obtained onmixing pre-set amounts of the sulfonating polymers, sulfonating agentsand the solvent and continuing the sulfonating reaction.

In the course of the sulfonating reaction, the concentration of thestyrene-based polymer is preferably 0.1 to 30 wt % and more preferably0.5 to 20 wt %. If the concentration is lower than this range, itbecomes difficult to introduce sulfone groups. If converselyconcentration is lower than this range, gelated products tend to beyielded during the sulfonating reaction or non-reacted substances areyielded in large quantities.

The reaction temperature for this sulfonating reaction is 0 to 100° C.and preferably 15 to 80° C. If the reaction temperature is lower thanthis range in the sulfonating reaction, the sulfonating reaction is lessliable to occur thus lowering the yield of the high-molecularflocculant.

In addition, in the present sulfonating reaction, the reaction timeduration, exclusive of the sulfonating agent dripping time, is 10minutes to 10 hours and preferably 30 minutes to 5 hours.

After the end of the sulfonating reaction of the solution, the sulfonegroups are neutralized by a neutralizing agent and subsequently thesolvent is distilled off to yield the desired high-molecular flocculant.

The neutralizing agent may be enumerated by oxides, hydroxides,carbonates, acetates, sulfonates, phosphates of basic compounds, such asalkali metals (sodium, lithium or potassium), alkali earth metals(magnesium or calcium), ammonia and a variety of amine compounds(primary to tertiary alkyl amines). This neutralizing agent is graduallyadded to the reaction system in the state of a solid or an aqueoussolution to neutralize the sulfone groups introduced into thestyrene-based polymer. The techniques for distilling off the solvent maybe the techniques of liquid separation or distillation.

With the high-molecular flocculant of the present invention, thusobtained, its molecular weight Mw needs to be 150000 to 600000. If themolecular weight of the styrene-based polymer in the high-molecularflocculant is less than 150000, not only is the flocculant effect forthe suspended substances in the liquid suspension lowered, but also thesuspended substances are dispersed. Conversely, if the molecular weightof the styrene-based polymer is not less than 600000, the suspendedsubstances are aggregated as coarse blocks such that optimum clarifyingeffects cannot be produced while the yielded cake is of high watercontent.

On the other hand, with the present high-molecular flocculant, not lessthan 40 mol % and preferably not less than 50 mol % of sulfone groupsare introduced into the styrene-based polymer. If the content of thesulfone groups in the styrene-based polymer is smaller than 40 mol %,the high-molecular flocculant is lowered in solubility in water, thussignificantly lowering the flocculant effect for the starting materialin the liquid suspension.

For introducing a desired amount of sulfone groups, it is desirable forthe styrene units to be contained in the styrene-based polymer in thehigh-molecular flocculant in an amount not less than 60 mol % andpreferably in an amount not less than 80 mol %. If the amount of styreneunits in the styrene-based polymer is less than 60 mol %, it becomesdifficult to obtain the high-molecular flocculant, having theabove-mentioned amount of sulfone groups by the sulfonating reaction.

Besides these high-molecular flocculants, flocculants of natural originmay be used in conjunction with the high-molecular flocculant of thepresent invention. The flocculants of natural origin may be enumeratedby ‘moroheiya’, its dried product and extracts, jelly-like portion ofthe tomato seeds, its dried product or extract.

The ‘moroheiya’ is an annual grass of the genus Corcorus of the classshinanoki cultivated in Arabian tropical areas such as Egypt, Syria,Jordan or Iran, and is used from old as food as green to yellowvegetables. The viscous acidic polysaccharides as main component of themoroheiya are used as flocculant.

Specifically, the flower, stalk, root or portions thereof of moroheiyaare turned into paste which is used as the flocculant. Alternatively,the flower, stalk, root or portions thereof of moroheiya are dried andpulverized in a mixer to produce powders which are used as theflocculant. For drying the moroheiya, drying in the sun, air in shade,vacuum drying, hot air drying or freeze drying may be optionallyemployed.

The tomato is an annual plant of the class eggplant in the temperatezone and used from old as food as green to yellow vegetables. It is thejelly-like portion around the tomato seed that is used as theflocculant.

Specifically, the jelly-like portion around the tomato seed ispulverized directly or in the dried state by a mixer to produce powderswhich are used as the flocculant. For drying, the techniques similar tothose for the moroheiya are used.

Further, the paste or powders of the moroheiya or the jelly-shapedportion around the tomato seed or its dried product are processed byextraction with water, warm water, hydrophilic organic solvents(alcohols, ethers, N,N-dimethyl formamide or dimethyl sulfoxide sugar,or mixtures thereof, to produce a liquid extract which is used as theflocculant. The liquid extract may also be fractionated or dried for useas the flocculant. The liquid extract may preferably be water or warmwater.

The liquid extract may be re-precipitated in an organic solvent as apoor solvent or the re-precipitated product may further be dried for useas a flocculant.

The liquid extract may be freed from solid substances by filtration, ifso desired.

The alkalis may be ammoniac water, various amine compounds, sodiumhydroxide, potassium hydroxide, potassium hydroxide and sodiumcarbonate. The acids may be organic acids, such as lactic acid, butyricacid, acetic acid or formic acid, and inorganic acids, such as sulfuricacid, hydrochloric acid and nitric acid.

Of course, the viscous portion of moroheiya and around tomato seeds maydirectly be used as the flocculant. However, it is more effective to usethe viscous portions as powders or liquid extract for facilitating thediffusion in the processing liquid (liquid suspension). Also, theviscous portions of moroheiya and around tomato seeds, processed withextraction with water, warm water or water-soluble organic solvents, aremore meritorious than the directly dried viscous portions in flocculanteffect per unit weight of the same solid substance.

If the polysaccharide component of moroheiya or the viscous portionsaround tomato seeds are pulverized or heated excessively, thesecomponents are lowered in flocculant activity due to the lowering of themolecular weight caused by cutting of the main and side chains or due toinsolubility in water caused by the intramolecular cross-linkingreaction.

The high-molecular flocculant of the present invention may be used inconjunction with any of the above-mentioned flocculants. If thehigh-molecular flocculant of the present invention is used inconjunction with reverse type high-molecular flocculants, specialtechniques need to be used for effective processing.

If, for example, the high-molecular flocculant of the present inventionis charged positively, as when the high-molecular flocculant has amolecular structure portion added to with amino compounds such that itis converted to an acid salt or a quaternary ammonium salt, and if thehigh-molecular flocculant is used in conjunction with theabove-mentioned anionic high-molecular flocculant, the two flocculantsare of opposite polarities in water. Therefore, the flocculants arepreferably used sequentially rather than as a mixture. Similarly, if thehigh-molecular flocculant of the present invention is chargedpositively, as when cyano groups are converted to carboxylic group viacarbamoyl group, and if the high-molecular flocculant is used inconjunction with the above-mentioned cationic high-molecular flocculant,the two flocculants are of opposite polarities in water. Therefore, theflocculants are again preferably used sequentially rather than as amixture.

If the two flocculants are used sequentially, any one of the cationichigh-molecular flocculant and the anionic high-molecular flocculant maybe charged first into water for processing. However, if the water forprocessing is sewage water, the cationic high-molecular flocculant isusually charged first, since the usual sewage water is generallyprocessed with bactericidal treatment and hence the colloids are chargedto negative polarity.

In the water processing method of the present invention, thehigh-molecular flocculant of the present invention may also be used inconjunction with inorganic flocculants or flocculation assistant agents.

The inorganic flocculants may be enumerated by aluminum sulfate,aluminum polychloride, sodium aluminate, ferrous chloride, ferricchloride, ferric sulfate, copper chloride, modified basic aluminumsulfate (LACS) and activated silica.

The flocculation assistant agents may, for example, be enumerated byslaked lime, sodium silicate, bentonite and flyash.

These ingredients are generally added in amounts of 0.001 to 2000 ppmand preferably 0.1 to 500 ppm, related to waste water, depending on theconcentration of the starting material or the type of the dehydratingequipment.

Although there is no limitation to the type of the water for processingin accordance with the present invention, maximum effects can beproduced when the water for processing is highly contaminated water,such as plant waste water having inorganic particles as the startingmaterial.

The amount of addition of the high-molecular flocculant of the presentinvention to water for processing differs with the composition of thewater for processing and with the combination with other startingmaterial and the flocculation assistant agents. If the amount ofaddition is too small, the particles of the starting material cannot beflocculated sufficiently, whereas, if the amount is too large, theproportion of the high-molecular flocculant not contributing toflocculation is increased to lead to wastage of the high-molecularflocculant to give rise to renewed water contamination. The desirablerange of addition is generally 0.001 to 2000 ppm and more preferably 0.1to 500 ppm.

For processing waste water using the high-molecular flocculant of thepresent invention, coagulating agents, chelate resins, chelating agents,activated charcoal, ozonized water, ion exchange resins,water-absorptive resins, aqueous hydrogen peroxide, chlorine, liquidchlroline, sodium hypochlorite, chlorine dioxide, bleaching powder,chlorinated isocyan, diatomaceous earth, optical catalysts, such astitanium oxide, and biological processing agents, may be used.

Also, a variety of dehydrates, such as belt press dehydrator,centrifugal dehydrator or a screw press may be used. Dehydratedproducts, such as cakes, may be used for land filling using knowntechniques or converted into fuel or composts.

EXAMPLES

The present invention is hereinafter explained with reference toillustrative Examples based on experimental results.

[Modification of Cyano-group Containing High-molecular Waste Materialsby Addition of Amino Compounds]

First, the high-molecular waste material containing cyano groups isreacted with amino compounds to produce a high-molecular flocculant inorder to check into its properties.

The following three high-molecular waste materials, containing cyanogroups, we used in the following experiments.

The resulting powders were analyzed by Fourier transform IR absorptionspectrum (FT-IR) and nuclear magnetic resonance (NMR) spectrum. It wasfound that 80 mol % of cyano groups in the solid reaction product hadbeen converted to imidazoline rings and that these imidazoline ringswere not hydrolysed. The resulting powders were also soluble in water.

These powders were termed a high-molecular flocculant A. Thishigh-molecular flocculant A was of the nonionic type.

Example 2

An imidazoline ring containing polymer was obtained in the same way asin Example 1 except using 3.5 g of ethylene diamine as an aminocompound.

This polymer was dissolved in water and methyl chloride was injectedinto the resulting mass. The resulting product was reacted at 40° C. fortwo hours to yield an aqueous solution of a methyl chloride quaternarysalt polymer of imidazoline, while non-reacted methyl chloride wasdistilled off on heating.

The resulting product was termed a high-molecular flocculant B. Thishigh-molecular flocculant B was of the cationic type.

Example 3

1.0 g of small pieces of nitrile resin waste material b was dissolved in100 ml of dimethyl sulfoxide (DMSO). To the resulting mass were dripped2.3 g of ethanolamine at room temperature. The resulting mass wasstirred in situ and heated to 100° C. to carry out the reaction for 12hours.

After the end of the reaction, the reaction solution was poured intoethanol and precipitated. After filtration, the resulting product wasrinsed with methanol and dried in vacuo at room temperature. The aboveprocessing yielded a polymer in which 85% of the cyano groups werereplaced by an imino structure.

The resulting product was termed a high-molecular flocculant C. Thishigh-molecular flocculant C was of the cationic type.

Example 4

An imino group containing polymer was obtained in the same way as inExample 3 except using 2.8 g of butylamine as an amino compound.

This polymer was dissolved in water and admixed with an aqueous solutionof dilute sulfuric acid to set pH to 4.0 to obtain a sulfate polymersolution.

The resulting product was termed a high-molecular flocculant D. Thishigh-molecular flocculant D was of the cationic type.

Example 5

A high-molecular flocculant was produced in the same way as n Example 2except using SAN resin waste material c as a starting material.

This high-molecular flocculant was termed a high-molecular flocculant Ewhich was of the cationic type.

Example 6

The high-molecular flocculant C was dissolved in water and the resultingaqueous solution was heated at 90° C. for 15 hours. After the end of theheating, the aqueous solution was dried to produce powders, for whichthe Fourier transform IR absorption spectrum (FT-IR) and nuclearmagnetic resonance (NMR) spectrum were measured. By these measurements,it was confirmed that 70 mol % of the imino structure was hydrolysed andconverted to an amide structure.

This high-molecular flocculant was termed a high-molecular flocculant Fwhich was of the nonionic type.

Example 7

0.05 g of sulfur powdered and 1.0 g of small pieces of waste acrylicfiber material a were added to 20 g of ethylene diamine and reaction wascarried out at 110° C. for six hours. After the end of the 110° C.reaction, non-reacted ethylene diamine was distilled off by distillationin vacuo and the residual mass was dissolved in water and precipitatedwith acetone.

The precipitates were then filtered and dried in vacuo at roomtemperature to produce brown powders. For these powders, the Fouriertransform IR absorption spectrum (FT-IR) and nuclear magnetic resonance(NMR) spectrum were measured. By these measurements, it was confirmedthat 42 mol % of the cyano groups of the solid reaction product wereconverted to imidazoline rings, and 18 mol % thereof were convertedto—amino ethyl acrylamide which was a hydrolizate.

This polymer was then dissolved in water and a dilute aqueous solutionof hydrochloric acid was added to the solution to give an aqueoussolution of a hydrochlorate polymer.

This high-molecular flocculant was termed a high-molecular flocculant Gwhich was of the nonionic type.

[Evaluation of Flocculant Performance]

The flocculant performance of these high-molecular flocculants A to Gwere evaluated.

In the following set of test examples, the following flocculants wereused with a view to comparison or use with the inventive products.

-   Nonionic high-molecular flocculant H: commercial polyacrylamide-   cationic high-molecular flocculant I: methyl chloride quaternary    product of commercial polydimethyl amino ethyl acrylate (potent    cationic type)-   anionic high-molecular flocculant J: commercial polyacryl amide    partial hydrolyzate (mid anionic type)-   sulfonate of waste resin material K: sodium polystyrene sulfonate    (starting material: expanded styrene, sulfonation ratio: 80 mol %)-   hydrolyzate L of waste fiber: polyacrylonitrile hydrolyzate (acrylic    fibers processed with sodium hydroxide)-   flocculant M of natural origin: dried pulverized moroheiya leaves    Evaluation Test 1

A 1 wt % aqueous solution of kaoline was prepared and used as a liquidsuspension for evaluation of flocculation (this solution is hereinaftertermed a liquid suspension). 100 ml of this liquid suspension werecharged into a measuring cylinder with a co-plug having a capacity of200 ml. The high-molecular flocculant and conventional high-molecularflocculants for comparison were dripped into the liquid suspension usingmeasuring pipettes. The dripping amounts were set so that theconcentration of the high-molecular flocculant in the liquid suspensionwas equal to 4 ppm.

After dripping, the measuring cylinder was stopped with the plug andturned upside down and restored repeatedly ten times. The measuringcylinder was then restored to the stationary state to measure the rateof precipitation of the suspended particles and the turbidity of thesupernatant liquid. The measured results are shown in Table 1.

-   Acrylic fiber waste material a

waste material of acrylic fibers for underwear containing not less than95 mol % of acrylonitrile

-   nitrile resin waste material b

waste material of vessels for cosmetics containing not less than 90 mol% of acrylonitrile

-   SAN (styrene-acrylonitrile) resin waste material c

waste material of 8 mm cassette caging (transparent portions) containing40 mol % of acrylonitrile

The above three waste materials were processed into small-sized chipsfor use as starting material. The acrylic fiber waste material wassevered by scissors into small-sized chips with each side 5 mm or lessin length, while the nitrite resin waste material b and the SAN resinwaste material c were severed by a cutter type crusher into small-sizedchips not larger than 16 mesh for use as starting material.

Example 1

4 g of 1,3-propane diamine, 0.03 g of sulfur powders and 1.0 g of smallpieces of acrylic fiber waste material a were charged into 40 g ofcyclohexane and stirred in situ to carry out an addition reaction at 60°C. for four hours.

A green solid substance, precipitated on the bottom of the reactionvessel, was taken out and dissolved. The resulting solution was pouredinto a large quantity of acetone and precipitated.

The precipitate was then filtered and dried in vacuo at room temperatureto yield pale yellow powders.

TABLE 1 high appellation A C F G H molecular ion type Nonionic typeflocculant rate of precipitation 23 21 22 20 16 (m/n) turbidity (ppm) 12 8 10 13 32

It is seen from table 1 that nonionic high-molecular flocculants,modified by addition of the amino compound to the cyano group, showedmore satisfactory results in the rate of precipitation and in turbidityof the supernatant liquid than the conventional nonionic flocculant andexhibited superior flocculating performance.

Evaluation Test 2

The processed liquid, obtained on primary flocculation of waste waterfrom an electronic parts plant (pH 6.5, SS 1.5 wt %) was used as aliquid suspension for evaluation of flocculation.

100 ml of the liquid suspension were charged into a measuring cylinderwith a co-plug, having a capacity of 200 ml and each flocculant wasdripped into the liquid suspension using a measuring pipette. Thedripping amount was set so that the high-molecular flocculant in theliquid suspension will be of the concentration equal to 2 ppm. If twosorts of the liquid suspension were used together, these flocculantswere mixed together so that the above concentration will be equal to 1ppm.

After dripping, the measuring cylinder was stopped with the plug andturned upside down and restored repeatedly ten times. The measuringcylinder was then restored to the stationary state to measure the rateof precipitation of the suspended particles, turbidity of thesupernatant liquid and the water content of the cake obtained afterfiltration by a filter cloth. The measured results are shown in Table 2.

TABLE 2 high appellation A A + J F + J J molecular ion type Anionicflocculant rate of precipitation 23 28 25 16 (m/h) turbidity (ppm) 12  810 32 water content (%) 73 70 68 75

It is seen from table 2 that the high-molecular flocculant of thepresent invention was superior to the conventional anionic flocculant inthe rate of precipitation, turbidity of the supernatant liquid and inwater content of the cake. It has also been seen that the high-molecularflocculant of the present invention can further be improved inflocculation performance by using it as a mixture with commercialanionic flocculants.

Evaluation Test 3

A mixed sludge from a sewage processing plant (pH, 6.2; SS 2.5 wt %) wasput to a jar test.

First, 0.5 wt % per SS of a cationic high-molecular flocculant was addedto the sludge being agitated by a jar tester and agitated forflocculation. If two sorts of the high-molecular flocculant were used asa mixture, the charged amounts of the flocculants were set to 0.2 wt %per SS. To the resulting product was further added 0.2 wt % of theanionic high-molecular flocculant per SS and agitated for flocculation.

The flocculated mass was then allowed to stand and measurement was thenmade of the rate of precipitation of suspended particles, turbidity ofthe supernatant liquid and the water content of the cake obtained onfiltration. The measured results are shown in table 3.

TABLE 3 cationic flocculant B D E G B + M I I I anionic flocculant — J KL J — J K precipitation rate 37 41 44 42 45 24 29 27 (m/h) turbidity(ppm) 27 22 25 23 20 43 36 33 water content (%) 73 72 71 72 71 77 76 75

It is seen from table 3 that the high-molecular flocculant of thepresent invention was superior to the conventional anionic flocculant inthe rate of precipitation, turbidity of the supernatant liquid and inwater content of the cake both when used alone and when used inconjunction with the anionic flocculant. It has also been seen that thehigh-molecular flocculant of the present invention can further beimproved in flocculation performance by using it as a mixture withflocculants of natural origin.

[Modification of Waste High-molecular Material by Hydrolysis of CyanoGroups]

The following four high-molecular materials were used as base materialsfor hydrolysis in the respective Examples.

-   waste acrylic fibers d

waste acrylic fibers for underwear containing not less than 90 mol % ofacrylonitrile;

-   waste nitrile rubber e

waste oil-resistant rubber and hose material containing not less than 40mol % of acrylonitrile;

-   waste nitrile resin f

waste vessels for cosmetics containing not less than 90 mol % ofacrylonitrile;

-   SAN (styrene-acrylonitrile) waste resin g

waste battery casing material containing not less than 30 mol % ofacrylonitrile;

The waste material d was severed with scissors into small pieces eachhaving a side measuring 5 mm or less.

The waste material e was freeze-pulverized to small pieces eachmeasuring 32 mesh or less.

The waste materials f and g were pulverised to small pieces measuring 32mesh or less using a cutter type pulveriser.

Example 8

0.6 g of the waste material d was charged into 30 g of 96% sulfuric acidand agitated in in situ to carry out acidic hydrolysis at 50° C. for twohours. The waste material d was completely dissolved in sulfuric acid.

Next, this mixture was poured in a large quantity of acetone to yield awhite precipitate, which was further washed twice or thrice with acetoneand dried.

The dried powders were analyzed by measurement with the Fouriertransform IR absorption spectrum (FT-IR) and nuclear magnetic resonance(NMR) spectrum. By these measurements, it was confirmed that not lessthan 90 mol % of the cyano groups in the waste material d were convertedto carbamoyl groups and that carboxylic groups were generated under theabove-mentioned reaction conditions. These powders were also readilysoluble in water.

These powders were termed a high-molecular flocculant N. The ion type ofthis high-molecular flocculant N was the nonionic type.

Example 9

The acid hydrolysis was carried out by the same method as in Example 8except using the waste material e and setting the reaction temperatureand reaction time to 80° C. and 4 hours, respectively.

The FT-IR and NMR measurements, conducted on the resulting powders,revealed that not less than 90 mol % of the cyano groups in the wastematerial e were converted to carbamoyl groups and that no carboxylicgroups were generated under the above-mentioned reaction conditions.These powders were also readily soluble in water.

These powders were termed a high-molecular flocculant O. The ion type ofthis high-molecular flocculant O was the nonionic type.

Example 10

The acid hydrolysis was carried out by the same method as in Example 8except using the waste material f and setting the reaction temperatureand reaction time to 80° C. and 4 hours, respectively.

The FT-IR and NMR measurements, conducted on the resulting powders,revealed that not less than 90 mol % of the cyano groups in the wastematerial f were converted to carbamoyl groups and that no carboxylicgroups were generated under the above-mentioned reaction conditions.These powders were also readily soluble in water.

These powders were termed a high-molecular flocculant P. The ion type ofthis high-molecular flocculant P was the nonionic type.

Example 11

The acid hydrolysis was carried out by the same method as in Example 8except using the waste material g and setting the reaction temperatureand reaction time to 80° C. and 4 hours, respectively.

The FT-IR and NMR measurements, conducted on the resulting powders,revealed that not less than 90 mol % of the cyano groups in the wastematerial g were converted to carbamoyl groups and that no carboxylicgroups were generated under the above-mentioned reaction conditions.These powders were also readily soluble in water:

These powders were termed a high-molecular flocculant Q. The ion type ofthis high-molecular flocculant Q was the nonionic type.

Example 12

1 g of the waste material d was charged into 40 g of cyclohexane and, asthe temperature of the reaction system was controlled to 25 to 30° C.,1.8 g of sulfuric anhydride was dripped over 30 minutes. After the endof dripping, agitation was continued for further 30 minutes. 30 g ofwater were added to the reaction system to carry out hydrolysis at 30°for one hour.

The reaction mixture was distilled in vacuo to remove cyclohexane andthe residual liquid was adjusted to pH of 6 to produce a high-molecularaqueous solution. The FT-IR and NMR measurements, conducted on theresulting high-molecular aqueous solution, revealed that not less than90 mol % of the cyano groups in the waste material d were converted tocarbamoyl groups and that no carboxylic groups were generated under theabove-mentioned reaction conditions. These powders were also readilysoluble in water.

These powders were termed a high-molecular flocculant R. The ion type ofthis high-molecular flocculant R was the nonionic type.

Example 13

To a 1%-aqueous solution of the high-molecular flocculant N, obtained inExample 8, sodium hydroxide (NaOH) equivalent to 50 mol % of carbamoylgroups of the high-molecular flocculant N was added to carry outalkaline hydrolysis at 80° C. for one hour.

The FT-IR and NMR measurements, conducted on the resultinghigh-molecular aqueous solution, revealed that, of the carbanoyl groupsof the high-molecular flocculant N, 90 mol % of the added amount ofNaOH, corresponding to 45 mol % of the initial carbamoyl group content,were converted to sodium salt type carboxylic groups.

These powders were termed a high-molecular flocculant S. The ion type ofthis high-molecular flocculant S was the anionic type.

Example 14

To a 1%-aqueous solution of the high-molecular flocculant R, obtained inExample 12, sodium hydroxide (NaOH) in an equimolar amount to carbamoylgroups of the high-molecular flocculant R was added to carry outalkaline hydrolysis at 80° C. for one hour.

The FT-IR and NMR measurements, conducted on the resultinghigh-molecular aqueous solution, revealed that, of the carbamoyl groupsof the high-molecular flocculant R, 90 mol % of the added amount ofNaOH, corresponding to 90 mol % of the initial carbamoyl group content,were converted to sodium salt type carboxylic groups.

These powders were termed a high-molecular flocculant T. The ion type ofthis high-molecular flocculant T was the anionic type.

The high-molecular flocculants obtained in Examples 8 to 14 areindicated collectively in Table 4.

TABLE 4 Starting material and Acrylonit rile Content of Appellation andhydrolysis type (catalysts for content in functional groups ion type ofhigh- hydrolysis are given in starting material after modificationmolecular Ex. parentheses) (mol %) (mol %) State of products flocculant8 Waste acrylic fibers: d; acidic >90 —CN <9  Water-soluble, N: nonionichydrolysis (concentrated —CONH₂ >81 white powders sulfuric acid) —COOH —9 Waste nitrile rubber: e; acidic >40 —CN <4  Water-soluble, O: nonionichydrolysis (concentrated —CONH₂ >36 white powders sulfuric acid) —COOH —10 Waste nitrile rubber: f; acidic >90 —CN <9  Water-soluble, P:nonionic hydrolysis (concentrated —CONH₂ >81 white powders sulfuricacid) —COOH — 11 Waste styrene-acrylonitrile >30 —CN <3  Water-soluble,Q: nonionic resin: g; acidic hydrolysis —CONH₂ >27 white powders(concentrated sulfuric acid) —COOH — 12 Waste acrylic fibers: d;acidic >90 —CN <9  High-molecular R: nonionic hydrolysis (sulfuricanhydride) —CONH₂ >81 aqueous solution —COOH — 13 Product N of Ex. 8;acidic >90 —CN <9  High-molecular S: nonionic hydrolysis (concentrated—CONH₂ >45 aqueous solution sulfuric acid) + alkaline —COOH >36hydrolysis (NaOH) 14 Product R of Ex. 12; acidic >90 —CN <9 High-molecular T: nonionic hydrolysis (sulfuric anhydride) + alkaline—CONH₂ >8  aqueous solution hydrolysis (NaOH) —COOH >73

In Table 4, the content of the as-modified functional groups refers tothe total number of mols of the monomeric units making up thehigh-molecular material.

[Evaluation of Flocculating Performance]

Next, the flocculating performance of the high-molecular flocculants Nto T was evaluated.

In the following set of the evaluation tests, the following twocommercial high-molecular flocculants U, V were used with a view tocomparison and conjunctive use with the inventive products.

-   High molecular Flocculant U

partial hydrolyzate of polyacrylamide portion (hydrolyzation rate, 20mol %), anionic type

-   High molecular Flocculant V

Methyl chloride quaternary product of dimethyl amino ethyl acrylate,potent cationic type

Evaluation Test 4

0.2 wt % of aluminum sulfate as added to a 4 wt %-aqueous solution ofkaoline to give a colloidal liquid suspension for flocculationevaluation (referred to hereinafter as liquid suspension).

100 ml. of this liquid suspension were charged into a measuring cylinderwith a co-plug having a capacity of 200 ml. The high-molecularflocculants N to T and conventional high-molecular flocculants forcomparison were dripped into the liquid suspension using measuringpipettes. The dripping mounts were set so that the concentration of thehigh-molecular flocculant in the liquid suspension was equal to 5 ppm.

After dripping, the measuring cylinder was stopped with the plug andturned upside down and restored repeatedly ten times. The measuringcylinder was then restored to the to the stationary state to measure therate of precipitation of the suspended particles and the turbidity ofthe supernatant liquid.

The measured results are shown in Table 5.

TABLE 5 high- a N O P Q R S T U molecular ion nonionic anionicflocculant rate of 15 13 14 13 16 17 18 10 precipitation (m/h) turbidity(ppm) 35 45 43 48 32 28 25 50

On comparison of the flocculating performance of the high-molecularflocculants N to T of the present invention according to ion types, theanionic type high-molecular flocculants S and T are superior to thenonionic type high-molecular flocculants N to R. Therefore, inflocculating the colloidal system in which kaoline is flocculatedprimarily with aluminum sulfate used in the present Example, the anionictype high-molecular flocculants S and T may be said to be superior tothe hydrogen bonded type nonionic high-molecular flocculants N to R.

Thus, on comparing the flocculating performance of the same anionic typeflocculants, the anionic type high-molecular flocculants S and T of thepresent invention are superior to the conventional anionic typehigh-molecular flocculant. Moreover, the conventional product U wasinferior in performance the nonionic type high-molecular flocculants Nto R of the present invention.

This indicated the superior flocculating performance of the inventiveproducts.

Evaluation Test 5

500 ppm of aluminum sulfate were added to the waste water of anelectronic parts plant (pH, 4.8; mass of the floating substance (SS) of1.2 wt %) to prepare a liquid suspension for flocculation evaluation(referred to hereinafter as liquid suspension).

100 ml of this liquid suspension were charged into a measuring cylinderwith a co-plug having a capacity of 200 ml. An aqueous solution of thehigh-molecular flocculant was dripped into the liquid suspension usingmeasuring pipettes. The high-molecular flocculants used here were thenonionic high-molecular flocculants N, O, anionic high-molecularflocculants S, T and the conventional anionic high-molecular flocculantU.

The inventive products N, O and S were used as an 50-50 mixture with theconventional product U, whilst the inventive product T and theconventional product U were used alone. The high-molecular flocculantswere added in amounts which would give concentration of 10 ppm in theliquid suspension. Thus, if the two flocculants were used inconjunction, the inventive product and the conventional product are usedeach in the concentration of 5 ppm.

After dripping, the measuring cylinder was stopped with the plug andturned upside down and restored repeatedly ten times. The measuringcylinder was then restored to the stationary state to measure the rateof precipitation of the suspended particles and the turbidity of thesupernatant liquid. The precipitate yielded was dehydrated on a filtercloth to measure the water content in the cake.

The measured results are shown in table 6.

TABLE 6 high-molecular Inventive appellation N O S T — flocculant iontype nonionic anionic conventional U — U (anionic) rate of precipitation(m/h) 25 22 28 22 20 turbidity (ppm) 12 15 10  8 30 water content ofcake after 71 73 70 68 75 dehydration (ppm)

On comparing the case of using the high-molecular flocculant T of thepresent invention to that of using the conventional high-molecularflocculant U, as cases of using the sole high-molecular flocculant, theinventive product is superior in flocculating performance. It is notedthat these two flocculants are both of the anionic type. Theconventional product, inferior by itself to the inventive product, isimproved in flocculating performance on combination with the inventiveproducts N, O and S. This verified superior flocculating performanceproper to the inventive product.

However, in any of the above cases of combined use, the flocculatingperformance of the present invention in which anionic high-molecularflocculants T was used by itself could not be surpassed as far asturbidity was concerned. This is probably ascribable to the fact thatthe inventive product is smaller in molecular weight and higher inanionic efficiency than the conventional product.

Similar effects could be obtained when the commercial high-molecularflocculant used on mixing with the inventive product was changed to thenonionic type.

Evaluation Test 6

A jar test was conducted on a mixed sludge from a sewage processingplant (pH, 6.6; SS, 2.8 wt %). Specifically, as the above mixed sludgewas agitated by the jar tester, the commercial high-molecular flocculantV was added in a first step to the agitated sludge at a rate of 0.6 wt%. Then, at a second step, the high-molecular flocculants P, Q or T orthe conventional anionic high-molecular flocculant U was added each at arate of 0.15 wt % to the suspended particles.

After agitation, the liquid suspension was allowed to stand stationarilyand measurements were made of the rate of precipitation of the suspendedparticles and turbidity of the supernatant liquid. Also, the producedprecipitates were dehydrated on a filter cloth to measure the watercontent of the cake.

The measured results are shown in Table 7.

TABLE 7 high- Inventive appellation {circle around (2)}P {circle around(2)}Q {circle around (2)}T — molecular ion type Nonionic anionicflocculant Conventional {circle around (1)}*V (cationic) {circle around(1)}V (cationic) {circle around (2)}P (anionic) rate of precipitation(m/h) 41 38 44 33 turbidity (ppm) 25 28 22 38 water content of cakeafter 72 73 71 75 dehydration (ppm) *{circle around (1)} and {circlearound (2)} denote first and second stages, respectively.

In general, if the composition of the suspended particles is complex orcannot be known correctly, static charges of the colloidal particles isalso thought to be nonuniform. It is therefore thought to be effectiveto use the high-molecular flocculant of the cationic type and that ofthe nonionic type simultaneously. On comparison of the combination ofthe conventional cationic type flocculant and the conventional cationictype flocculant to the combination of the cationic and anionic typeinventive products, it has been found that the combination of theinventive products manifested superior flocculant effects.

In particular, the optimum flocculating effects can be obtained oncombining the conventional high-molecular flocculant and the inventivehigh-molecular flocculant.

Although cationic high-molecular flocculant cannot as a principle bemanufactured on hydrolysis of cyano groups, waste water processing canbe achieved more effectively by using the inventive flocculant incombination with the cationic commercial flocculant.

Although the preferred embodiments of the present invention and theresults of evaluating tests have been explained in the foregoing, itshould be noted that these embodiments have been given for illustrationpurposes and are not intended for limiting the scope of the invention.Specifically, the present invention can be optionally modified as to thetypes of the starting materials for the high-molecular flocculant orconditions for addition reaction, hydrolytic reaction, acid saltformation or water processing.

1. A method for producing a high-molecular weight flocculant comprisingthe step of: hydrolyzing a high-molecular weight polymeric materialhaving at least one cyano group thereby converting at least a portion ofsaid at least one cyano group into at least one carbamoyl group.
 2. Themethod according to claim 1 wherein said hydrolyzing step occurs in thepresence of an acidic catalyst.
 3. The method according to claim 1, saidhydrolyzing step further comprises the steps of (a) employing an acidiccatalyst; and (b) employing a basic catalyst, wherein, said at least onecarbamoyl group is converted into at least one carboxylic group or saltsthereof.
 4. The method according to claim 1 wherein said high-molecularweight polymeric material comprises acrylonitrile as a monomer unit. 5.The method according to claim 1 wherein said polymeric material isselected from the group consisting of acrylic fibers, nitrite resins,styrene-acrylonitrile resins, acrylonitrile-butadiene-styrene resins,acrylonitrile-styrene-acrylic resins, acrylonitrile-chlorinatedpolyethylene-styrene resins, nitrite rubbers and acrylonitrile-butadienerubbers.
 6. The method according to claim 1 wherein said polymericmaterial comprises at least one cyano group wherein said at least onecyano group comprises not less than 15 mol % of the total monomer unitspresent in said polymeric material.